Hydraulic press control circuit embodying fluid pressure intensifying means



June I3, 1950 H. M. PURCELL 2,511,541

HYDRAULIC PRESS CONTROL CIRCUIT EMBODYING FLUID PRESSURE INTENSIFYINGMEANS Filed July 8, 1947 2 Sheets-Sheet l M INVENTOR a NE D Mn PUWCfiLLATTORNEYEM June 13, 1950 H. M. PURCELL 2,511,541

HYDRAULIC PRESS CONTROL CIRC UIT EMBODYING FLUID PRESSURE INTENSIFYINGMEANS Filed July 8, 1947 2 Sheets-Sheet 2 ITEA- 7 WORK gwucxnfot, HOWARDM. PURCELL Patented June 13, 1950 HYDRAULIC PRESS CONTROL CIRCUIT EM-BODYING FLUID PRESSURE INTENSIFY- ING MEANS Howard M. Purcell,Philadelphia, Pa., assignor to H-P-M Development Corporation,

Wilmington,

DeL, a corporation oi Delaware Application July 8, 1947, Serial No.759,674

8 Claims. (01. 60-52) This invention relates to hydraulic pressactuating systems, and especially to such systems characterized by highpressures.

The particular object of this invention is to provide an improved highpressure actuating circuit for a hydraulic press.

It is another object of this invention to provide a high pressureactuating circuit for a hydraulic press which employs a minimum ofvalves.

Another object'of this invention is to provide a press actuating circuitincluding a hydraulic intensifier which may be made operative in eitherdirection of movement of the press ram.

Still another object is to provide a hydraulic press actuating circuitin which the press ram is normally operated by the discharge from a pumpand in which there is an intensifier which becomes operativeautomatically at a predetermined pressure in either direction ofmovement of the press ram.

A still further object is to provide a press operating circuit includinga pressure intensifier in which the shift over from low to highoperating pressures is accomplished smoothly and positively.

These and other objects and advantages will become more apparent uponvreference to the following description taken in connection with theaccompanying drawings in which:

Figure 1 is a diagrammatic view of a press operating circuit accordingto this invention;

Figure 2 is a diagrammatic wiring diagram of.

This invention generally is concerned with a hydraulic press actuatingcircuit in which there is a pump connected to supply eitherthe advancingor the retracting side or a press ram. This pump is preferably areversible type pump but itwill be understood that a one way deliverypump and a reversing valve could be employed in place of a reversiblepump if desired.

v The aforementioned reversible pump is connected between the advancingand retracting means and there is preferably a solenoid which may beenergized to bring about the delivery of the said pump to the advancingmeans. Upon de-energizing the said solenoid, the delivery of the pump isautomatically reversed to bring about a supply to the retracting meansof the press ram. Connected between the opposite ports of the pump is acheck valve which has therein a. movable member. The check valve alsocomprises a third port and in response to a pressure at either of thefirst two ports the movable valve member of the check valve moves toconnect the third port therewith. In this manner, the discharge side ofthe pump is always connected with the third port of the check valve.

The aforementioned third port is connected with the inlet of a hydraulicintensifier which discharges to a valve that is automatically operableto direct the said discharge eitherto the advancing means of the pressrain or the retracting means thereof, depending upon which direction thepress ram is moving. A motor is connected with the intensifier and isselectively operable to drive the intensifier for making it efiective inresponse to a predetermined pressure acting on which ever of theadvancing or retracting means of the press ram the pump is supplying atthe time. A hydraulic intensifier of this nature is fully shown anddescribed in the U. S. Patent to Warren R; Tucker, No. 2,486,079, issuedOctober 25, 1949, and assigned to the same assignee as the instantapplication.

The arrangement briefly described above includes no shiftable valvesexcept for the check valvegwhich are directly responsive to pressures inthe conduits connected therewith. These valves are of simpleconstruction and there is little likelihood that they will warp and bindunder the high pressures passing therethrough as isthe case withordinary operating valves such as fourway piston type valves, or rotaryvalves.

Structural arrangement Referring more particularly to the drawings,

there is shown a press cylinder at Ill within which.

pump I4 is connected through a valve generally indicated at IS with theretracting side of the ram.

The valve 18 comprises a body portion 20 havin; ports opening from thetop and bottom thereof, and also having a port opening from the sideintermediate the said top and bottom ports. Within the valve body 26there is a valve member 22 which, as shown, may comprise a ball. Thevalve member 22 is movable toward either end of the body 26 todisconnect the port at that end from the port opening from the side ofthe valve and to connect the said side opening port with the port in theother end of the valve body. As shown there is a spring 24 whichnormally urges the ball upwardly to seat against the port in the upperend or the body 20.

Connected between the two ports of the pump l4 there is another valve 26which has a side opening port 26 therein connected with the inlet of thepressure intensifier 36. The valve 26 is provided with a valve member orball which is movable within the valve in response to positive pressuresat either of the ports of the pump I4 to connect the pressure port ofthe pump with the inlet of the intensifier 30. The discharge port of theintensifier 30 is connected with the side opening port of a third valve32 which is constructed similarly to the valves l8 and 26. The upperport of the valve 32 is connected to the discharge side of the checkvalve it while the lower port is connected with the upper port of thevalve i8.

For supplying make-up fluid to the pump [4 in either direction ofdelivery thereof there are a pair of check valves 36 which have theiroutlets connected with opposite sides of the ram l2 by way of valves l6and I8 and their inlets connectedby a conduit 38 with the reservoir 40.

The exhaust conduit 42 of the intensifier also discharges directly intothe reservoir 40.

The advancing side of the press ram is adapted for being connecteddirectly with the reservoir by means of a surge valve 44. This valve isnormally closed but may open by suction in the advancing means forpermitting fluid to flow thereto from the reservoir 40, or will open inresponse to predetermined pressure conducted thereto by the conduit 46leading to the retracting means for theram l2.

As shown in more detail in Fig. 4, the surge valve 44 has formed thereina lower chamber 44a which communicates with the advancing area of theram by way of the ports 44b.- Slidably carried within the lower chamber44b of the valvev is the lower head 44c of a movable valve memadvancingarea of the ram, and in response to such a suction, the lower head 440of the valve 44 is displaced from its normal position of closure withrespect to the channel 440 to permit make-up fluid to enter theadvancing area of the ram. Thereafter, as thepress platen meets the workand pressure within the advancing area builds up, the valve will onceagain close and permit pump pressure to work upon the ram. As mentionedbefore, the surge valve 44 is also effective upon a retraction stroke toopen the advancing area of the ram to the reservoir. This latter openingof the valve is eifected by a predetermined pressure build-up within theretracting area of the ram, which pressure is transferred through theconduit 46 to act upon the upper head 44c of the valve member andthereby to displace the same downwardly and unseat the lower head 440.This provision is made for the purpose of rapidly exhausting fluid fromthe relatively larger ram-advancing area during the introduction ofpressure fluid within the smaller ram-retracting area thereof.

Connected with the conduit between the check valve it and the advancingmeans of the ram l2 there is a pressure switch indicated as PSI andwhich is operable in response to a predetermined pressure to close apair of contacts.

Similarly, there is also a pressure switch PS2 connected with theconduit leading from the valve it! to the retracting means of the ram I2and also operative in response to a predetermined pressure to close apair of contacts. Still a third pressure operated switch indicated at Tis connected with the advancing means of the spective cylinders andthere is no passage of fluid ber 44d which is also provided with anupper.

enlarged head member 44c. The upper head 44c of the valve member isreciprocable in a second chamber 44f formed in the upper end of thevalve casing. Communicating with the upper end of the chamber 441 is oneend of the conduit 46 which, as beforementioned, has its opposite endconnected with the retracting area of the ram 12. Extending through thevalve casing and communicating with the interior of the reservoir 40 isa Y-shaped channel or port 449 which is also adapted to communicate withthe lower chamber 44a of the valve. I

In operation, the lower head 44c of the movable valve member normallycloses the channel 44c-with respect to the lower chamber 440 and theadvancing area of the ram l2, due to the action of the compressionspring 44h which is mounted between the lower wall of the chamber 44aand the under side of the lower head 440. During an advancing stroke,'where' the weight of the ram and press aid the pump discharge, thereoften times occurs a suction within the through the intensifier. Thus,there is a motor M connected with the valve member of the intensifierand which,'when energized, brings about a transfer of fluid from theside port of the valve 26 at one pressure to the side port of the valve32 at an intensified pressure.

The operating principle of the intensifier 36 is diagrammaticallyillustrated in Figure 5, wherein only one of a plurality of thepressureintensifying pistons 36a contained in the intensifler is shownin relation to the driven rotaryvalve member or distributor 30b. Inoperation, rotation of the distributor 3812), upon energization of themotor M, is effective to alter- I nately direct fluid under pressure ofthe pump 14 against the two pressure areas 340 and 36d of the piston 36awhile at the'same time connecting the opposite area Me with exhaust andthe smaller opposite area 36! with the work. Thus, pump pressure appliedto two faces of the .piston causes fluid discharged from the one smallerarea It] to'be more highly pressurized as the single area 301 isabsorbing the total force produced by the pump pressure acting upon theopposite two faces 30c and 30d. It will be understood, that theinterconnecting of the separate pressure faces 30c, d, e and I of thevarious pistons of the intensifier with the pump inlet, work outlet andexhaust ports, respectively, is accomplished solely by means of asuitable system andarrangement of ports within the rotary fluiddistributor III) in connection with a system of channels or passageswithin the housing of the intensifier leading to the separateintensifier pistons 30a, and that the proper distribution of fluid toand from the pistons is accomplished entirely within the intensifiercasing and thence to the respective work and exhaust outlets thereof.

It will further be understood that the illustration of the intensifieras shown in Figure is intended only as a graphic illustration of onlyone cycle in the operation of one of a plurality of identical pistonstages, and that the intensifier during operation is capable ofconstantly discharging fluid at a higher-than-pump' pressure, but at areduced volume due to the loss of fluid to exhaust.

The pump it has connected therewith any suitable linkage for reversingits delivery. v As shown there is a linkage ill which includes a-lever52 having a solenoid SI connected therewith which, when energized willactuate the linkage to shift the pump to bring about the deliverytherefrom to the advancing means oi the ram i2. When the solenoid SI isde-energized the spring 54 brings about the delivery of the pump to theretracting means of the ram l2. When the ram has retracted apredetermined amount an arm 56 on the platen 58 connected with the ram i2 actuates the linkage 50 to place the pump in neutral delivery positionthereby to halt the pres ram and platen.

The electrical circuit for controlling the energization of the solenoidSI and the motor M connected with the intensifier valve member is shownin Figure 2. Between the power lines Li and L2 and in series with thenormally'opened push button station 60 there is a contactor coil A.Bypassing the push button 60 there is a pair of normally opened contactsadapted for being connected by actuation-of the blade Al by energizationof the contact coil A and the normally closed pressure switch '1.Parallel withcoil A is the pump shifting solenoid SI. Also connectedbetween the power lines Li and L2 is the motor M in series with theparalleled and normally open pressure switches PSI and PS2. Upon closureof either of these pressure switches the motor M will be energized todrive the intensifier 30 and thereby to make the same effective.

In Figure 3 there is illustrated another type of check valve which maybe used in place of any of the valves iii, 26 or 32. The valve shown inFigure 3 is essentially identical with the aforementioned check valvesbut includes a cylindrical valve member 62 rather than a ball.

Operations In operation, the advancing stroke of the ram i2 is commencedby closing the Push button 60 whereupon the contactor coil A and thesolenoid Si are energized and a holding circuit therefor is establishedby the contactor blade At. The pump now delivers through the check valveIE to the advancing side of the rain l2. The retracting side of the raml2 discharges through the valve l8 to the lower port of l4. The initialmovement by the ram l2 takes place as rapidly as the pump it withdrawsfluid from beneath the ram 12 and the advancing'means is partiallyfilled through the surge valve 44. When the ram engages the work furthermovement thereof takes place by the delivery of the pump it to theadvancing means thereof and at this time make-up fluid enters the pumpthrough the lower of the check valves 38.

When pressure rises on the advancing means of the ram suificiently toclose the pressure switch PSI, the motor M commences to operate and theintensifier 30 delivers high pressure fluid to the side port of thevalve 32. It will be noted that at this time the valve member of thevalve 32 is in its lowermostposition so that the pressure fluid suppliedby the intensifier flows directly to the ram advancing means.

Upon the accomplishment of a predetermined higher pressure on the ramadvancing means, the switch T opens and de-energizes the coil A and thesolenoid SI. This permits the spring 54 to move the pump to deliver tothe retracting means of the press ram. The ram I! now moves upwardlywith fluid being deliveredthereto from the lower port of the pump l4through the valve l8, and with the advancing means thereof exhaustingthrough the surge valve 44 which is piloted open by pressure conductedthereto through theconduit 46.

Should the press ram meet resistance during its retracting movement, thepressure switch PS2 willclose and again make the intensifier 3Deffective to deliver a high pressure fluid to the side port of the valve32. At this time, the valve member of the valve 32 is in its uppermostposition and the high pressure fluid thus flows to the upper port of thevalve l8. This moves the valve member 22 thereof downwardly anddirects'the said high pressure fluid to the ram retracting means.vShould the resistance encountered by the ram drop, then the pressureboth the advancingand retracting means of the pressr'am.

As a modified arrangement, the springs shown in the check valves l8 and32 could be eliminated by so positioning the valves that the valvemembers thereof were normally positioned by gravity toward the" end towhich they are biased by their respective springs as shown in the drawlugs.

It will be understood that this invention is susceptible to modificationin order to adopt it to different usages and conditions and,accordingly, it is desired to comprehend such modifications within thisinvention as may fall within the scope of the appended claims.

I claim:

1. In a hydraulic circuit; a fluid motor having a pair of ports; areversible source of pressure fluid connected to supply pressure fluidto either of the ports of said motor; a fluid pressure intensifierhaving an inlet and an outlet and operable to receive fluid at the saidinlet and to redischarge it from said outlet at increased pressure;

. valve means connected between the inlet of said intensifier and theopposite sides of said source and operable to connect said inlet withthe delivery side of said source; a'second valve means connected betweenthe discharge side of said intensifier and the ports of said motor andoperable to connect the said discharge side with whichever oi said portsis under pressure; and means responsive to the accomplishment or apredetermined pressure at either of said motor ports for bringing aboutthe delivery oi high pressure fluid thereto from said intensifier.

2. In a hydraulic circuit; a fiuid'motor having a pair of ports; areversible pump connected between said ports; a fluid pressureintensifier having an inlet and an outlet and also having a valve memberwhich must be driven to make said intensifier effective; a first valveresponsive to pressure at either side oi said pump for connecting thatside with the inlet or said intensifier; other valve means responsive topressure at either of said motor ports for connecting that port with thedischarge side oi said intensifier; and means responsive to apredetermined pressure developed at the motor port withwhlclr'theflehaige side of said intensifier is connected for actuatingsaid drivable valve member to make said intensifier effective. 7

3. In a hydraulic circuit; a fluid motor having a pair of ports; areversible pump connected between said ports for supplying fluidpressure.

thereto; a fluid pressure intensifier having an inlet and an outlet andalso having a valve inem her which must be driven to make saidintensifier eii'ective; a shuttle valve connected between the oppositesides of said pump and the inlet 01' said intensifier and operableautomatically for conoutlet-oi said intensifier with whichever port ofsaid motor is under pressure, and to disconnect said pump therefrom; andmeans responsive to the accomplishment ot a predetermined pressure atthe port of the motor connected with the outlet or said intensifierioractuating said drivable valve member thereby to make said intensifierefiective.

4. In combination; a reversible delivery source of pressure fluid; afluid pressure intensifier having a low pressure inlet and a highpressure outlet; and a shuttle valve connected between the oppositesides of said source and the inlet oi said intensifier and including avalve member responsive to pressure at either or said sides forconnecting the said side with the inlet of said intensifier.

5'. In combination; a reversible delivery pump;

a fiuid pressure intensifier having a low pressure inlet and a highpressure outlet; a valve connect'ed between the opposite sides or saidpump and said inlet; and a valve member in said valve responsive topressure at either side oi said pump for connecting that side with saidinlet while simultaneously interrupting communication between said inletand the other side 0! said pump.

6. In a hydraulic circuit; a fluid motor having a pair of ports; areversible source of pressure fluid connected between said ports forsupplyingr actuating fluid to saidmptor; a fluid pressure 8 intensifierhaving an inlet and an outlet and adapted for receiving fluid at thesaid inlet and redischarging it from sald outlet at increased pressure;means responsive to the accomplishment 01' a predetermined pressure ateither of said motor ports for bringing about the delivery of highpressure fiuid from said intensifier, and

.means responsive to the accomplishment oi a said motor ports forbringing about the delivery necting said inlet with the pressure side ofsaid pump; other valve means operable to connect the of high pressurefluid from said intensifier, means responsive to the accomplishment of apredetermined higher pressure at one oi said motor ports for reversingthe source of preaure fluid, said fluid motor having a ram, and meanscarried by the ram to place the source oi fluid pressure inneutral whenthe ram i r'etracted a predetermined amount.

8. ma hydraulic control circuit; a fluid motor having a pair of ports; areversible source of pressure fluid connected between said ports iorsupplying actuating fluid to said motor; a driven fluid pressureintensifier having an inlet and an outlet and operable when driven toreceive fluid at the said inlet and redischarge at least a part of saidfluid from said outlet at increased pressures; a first valve meansconnected between said source and the inlet of said intensifier fordirecting pressure fluid discharged from said source to the inlet ofsaid intensifier; other valve means connected between the outlet or saidintensifier and the ports or said motor for establishing communicationbetween the outlet of said intensifier and whichever of said ports isreceivihg pressure from said source during operation 01' saidintensifier; and means responsive to a given maximum pressure at eitherof the ports of said motor for bringing said intensifier into operation.

HOWARD M.PURCELL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATEN'rs Number Name Date 2,255,560 Fieber Sept. 9, 19412,308,712 Peterson Jan. 19, 1943 2,366,388 Crosby Jan. 2,1945

